smb3: remove unused flag passed into close functions

close was relayered to allow passing in an async flag which
is no longer needed in this path.  Remove the unneeded parameter
"flags" passed in on close.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>